Merge pull request #378 from googlefonts/colrv1-handle-unknown-flags
Colrv1 handle unknown flags and don't include region indicators in noflags buildfeblend-soft-light-flags
rsheeter
GitHub
commit
e667644ec5
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@ -54,32 +54,6 @@ srcs = [
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"../svg/emoji_u1f198.svg",
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"../svg/emoji_u1f199.svg",
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"../svg/emoji_u1f19a.svg",
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"../svg/emoji_u1f1e6.svg",
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"../svg/emoji_u1f1e7.svg",
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"../svg/emoji_u1f1e8.svg",
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"../svg/emoji_u1f1e9.svg",
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"../svg/emoji_u1f1ea.svg",
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"../svg/emoji_u1f1eb.svg",
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"../svg/emoji_u1f1ec.svg",
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"../svg/emoji_u1f1ed.svg",
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"../svg/emoji_u1f1ee.svg",
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"../svg/emoji_u1f1ef.svg",
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"../svg/emoji_u1f1f0.svg",
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"../svg/emoji_u1f1f1.svg",
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"../svg/emoji_u1f1f2.svg",
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"../svg/emoji_u1f1f3.svg",
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"../svg/emoji_u1f1f4.svg",
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"../svg/emoji_u1f1f5.svg",
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"../svg/emoji_u1f1f6.svg",
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"../svg/emoji_u1f1f7.svg",
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"../svg/emoji_u1f1f8.svg",
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"../svg/emoji_u1f1f9.svg",
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"../svg/emoji_u1f1fa.svg",
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"../svg/emoji_u1f1fb.svg",
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"../svg/emoji_u1f1fc.svg",
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"../svg/emoji_u1f1fd.svg",
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"../svg/emoji_u1f1fe.svg",
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"../svg/emoji_u1f1ff.svg",
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"../svg/emoji_u1f201.svg",
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"../svg/emoji_u1f202.svg",
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"../svg/emoji_u1f21a.svg",
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@ -5,11 +5,13 @@ For now substantially based on copying from a correct bitmap build.
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"""
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from absl import app
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import functools
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from fontTools.feaLib.builder import addOpenTypeFeaturesFromString
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from fontTools import ttLib
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from fontTools.ttLib.tables import _g_l_y_f as glyf
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from fontTools.ttLib.tables import otTables as ot
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import map_pua_emoji
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from nototools import add_vs_cmap
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from nototools import font_data
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from nototools import unicode_data
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from pathlib import Path
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@ -95,12 +97,13 @@ def _add_cmap_entries(colr_font, codepoint, glyph_name):
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print(f"Map 0x{codepoint:04x} to {glyph_name}, format {table.format}")
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def _map_missing_flag_tag_chars_to_empty_glyphs(colr_font):
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# Add all tag characters used in flags
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tag_cps = set(range(0xE0030, 0xE0039 + 1)) | set(range(0xE0061, 0xE007A + 1))
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FLAG_TAGS = set(range(0xE0030, 0xE0039 + 1)) | set(range(0xE0061, 0xE007A + 1))
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CANCEL_TAG = 0xE007F
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# Cancel tag
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tag_cps |= {0xE007F}
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def _map_missing_flag_tag_chars_to_empty_glyphs(colr_font):
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# Add all tag characters used in flags + cancel tag
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tag_cps = FLAG_TAGS | {CANCEL_TAG}
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# Anything already cmap'd is fine
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tag_cps -= set(_Cmap(colr_font).keys())
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@ -143,28 +146,6 @@ def _Cmap(ttfont):
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return functools.reduce(_Reducer, unicode_cmaps, {})
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def _map_empty_flag_tag_to_black_flag(colr_font):
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# fontchain_lint wants direct support for empty flag tags
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# so map them to the default flag to match cbdt behavior
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# if the emoji font starts using extensions this code will require revision
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cmap = _Cmap(colr_font)
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black_flag_glyph = cmap[0x1F3F4]
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cancel_tag_glyph = cmap[0xE007F]
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lookup_list = colr_font["GSUB"].table.LookupList
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liga_set = _ligaset_for_glyph(lookup_list, black_flag_glyph)
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assert liga_set is not None, "There should be existing ligatures using black flag"
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# Map black flag + cancel tag to just black flag
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# Since this is the ligature set for black flag, component is just cancel tag
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# Since we only have one component its safe to put our rule at the front
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liga = ot.Ligature()
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liga.Component = [cancel_tag_glyph]
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liga.LigGlyph = black_flag_glyph
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liga_set.insert(0, liga)
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def _add_vertical_layout_tables(cbdt_font, colr_font):
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upem_scale = colr_font["head"].unitsPerEm / cbdt_font["head"].unitsPerEm
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@ -201,6 +182,112 @@ def _add_vertical_layout_tables(cbdt_font, colr_font):
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vmtx.metrics[gn] = height, 0
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UNKNOWN_FLAG_PUA = 0xFE82B
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BLACK_FLAG = 0x1F3F4
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REGIONAL_INDICATORS = set(range(0x1F1E6, 0x1F1FF + 1))
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def _add_fallback_subs_for_unknown_flags(colr_font):
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"""Add GSUB lookups to replace unsupported flag sequences with the 'unknown flag'.
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In order to locate the unknown flag, the glyph must be mapped to 0xFE82B PUA code;
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the latter is removed from the cmap table after the GSUB has been updated.
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"""
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cmap = _Cmap(colr_font)
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unknown_flag = cmap[UNKNOWN_FLAG_PUA]
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black_flag = cmap[BLACK_FLAG]
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cancel_tag = cmap[CANCEL_TAG]
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flag_tags = sorted(cmap[cp] for cp in FLAG_TAGS)
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# in the *-noflags.ttf font there are no region flags thus this list is empty
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regional_indicators = sorted(cmap[cp] for cp in REGIONAL_INDICATORS if cp in cmap)
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classes = f'@FLAG_TAGS = [{" ".join(flag_tags)}];\n'
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if regional_indicators:
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classes += f"""
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@REGIONAL_INDICATORS = [{" ".join(regional_indicators)}];
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@UNKNOWN_FLAG = [{" ".join([unknown_flag] * len(regional_indicators))}];
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"""
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lookups = (
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# the first lookup is a dummy that stands for the emoji sequences ligatures
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# from the destination font; we only use it to ensure the lookup indices match.
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# We can't leave it empty otherwise feaLib optimizes it away.
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f"""
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lookup placeholder {{
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sub {unknown_flag} {unknown_flag} by {unknown_flag};
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}} placeholder;
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"""
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+ "\n".join(
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["lookup delete_glyph {"]
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+ [f" sub {g} by NULL;" for g in sorted(regional_indicators + flag_tags)]
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+ ["} delete_glyph;"]
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)
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+ (
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"""
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lookup replace_with_unknown_flag {
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sub @REGIONAL_INDICATORS by @UNKNOWN_FLAG;
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} replace_with_unknown_flag;
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"""
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if regional_indicators
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else "\n"
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)
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)
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features = (
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"languagesystem DFLT dflt;\n"
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+ classes
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+ lookups
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+ "feature ccmp {"
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+ f"""
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lookup placeholder;
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sub {black_flag} @FLAG_TAGS' lookup delete_glyph;
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sub {black_flag} {cancel_tag} by {unknown_flag};
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"""
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+ (
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"""
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sub @REGIONAL_INDICATORS' lookup replace_with_unknown_flag
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@REGIONAL_INDICATORS' lookup delete_glyph;
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"""
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if regional_indicators
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else ""
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)
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+ "} ccmp;"
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)
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# feaLib always builds a new GSUB table (can't update one in place) so we have to
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# use an empty TTFont and then update our GSUB with the newly built lookups
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temp_font = ttLib.TTFont()
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temp_font.setGlyphOrder(colr_font.getGlyphOrder())
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addOpenTypeFeaturesFromString(temp_font, features)
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temp_gsub = temp_font["GSUB"].table
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# sanity check
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assert len(temp_gsub.FeatureList.FeatureRecord) == 1
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assert temp_gsub.FeatureList.FeatureRecord[0].FeatureTag == "ccmp"
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temp_ccmp = temp_gsub.FeatureList.FeatureRecord[0].Feature
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colr_gsub = colr_font["GSUB"].table
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ccmps = [
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r.Feature for r in colr_gsub.FeatureList.FeatureRecord if r.FeatureTag == "ccmp"
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]
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assert len(ccmps) == 1, f"expected only 1 'ccmp' feature record, found {len(ccmps)}"
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colr_ccmp = ccmps[0]
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colr_lookups = colr_gsub.LookupList.Lookup
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assert (
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len(colr_lookups) == 1
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), f"expected only 1 lookup in COLRv1's GSUB.LookupList, found {len(colr_lookups)}"
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assert (
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colr_lookups[0].LookupType == 4
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), f"expected Lookup[0] of type 4 in COLRv1, found {colr_lookups[0].LookupType}"
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colr_lookups.extend(temp_gsub.LookupList.Lookup[1:])
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colr_gsub.LookupList.LookupCount = len(colr_lookups)
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colr_ccmp.LookupListIndex = temp_ccmp.LookupListIndex
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colr_ccmp.LookupCount = len(colr_ccmp.LookupListIndex)
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# get rid of the Unknown Flag private codepoint as no longer needed
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font_data.delete_from_cmap(colr_font, [UNKNOWN_FLAG_PUA])
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def main(argv):
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if len(argv) != 3:
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raise ValueError(
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@ -233,12 +320,12 @@ def main(argv):
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_map_missing_flag_tag_chars_to_empty_glyphs(colr_font)
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_map_empty_flag_tag_to_black_flag(colr_font)
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add_soft_light_to_flags(colr_font)
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_add_vertical_layout_tables(cbdt_font, colr_font)
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_add_fallback_subs_for_unknown_flags(colr_font)
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out_file = Path(_OUTPUT_FILE[colr_file.name]).absolute()
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print("Writing", out_file)
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colr_font.save(out_file)
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